Chair



D. POWELL- 2,1

\ CHAIR Filed Oct. 12, 1957 Dec. 6, 1938.

Dwgh Po well? Patented Dec. 6, 1938 ITED* STATES PATENT 'OFFICE CHAIR Application October 12, 1937, Serial No. 168,658

1 Claim.

This invention relates to furniture, and more particularly to office chairs of the posture type.

One of the objects of the invention is to provide a novel back construction which not only has the capacity to be tilted and Vertically adjusted with reference to the seat, but which also includes a back rest whose angular position may be Varied with reference to the back structure proper thereby to afford maximum comfort to the occupant of the Chair. t

Another object of the invention is to provide a novel adjusting unit carried by the frame members which support the back rest which Will permit adequately j adjusting the lower portion of the back rest with reference to its normal relaton to the seat and frame, and which may be readiIy and quickly manipulated as desired.

A further object is to provide a back rest which is so mounted that if it is attempted to move the unoccupied Chair by grasping the upper portion of the back rest the latter will swing in one direction to avoid tipping the ,Chair over.

With the above and Other objects in view which will more readily appear as the nature of the invention is better understood the same consists in the novel construction, combination and arrangement of parts, hereinafter more fully described, illustrated and claimed.

A preferred and practical embodiment of the invention is shown in the accompanying drawing in which:

Figure 1 is a side elevation of a posture Chair constructed in accordance with the present invention, a portion thereof being in section.

Figure 2 is a rear elevaton of the construction shown in Figure 1.

Figure 3 is an enlarged detail view of the back rest adjusting means.

Figure 4 is a detail transverse Cross-sectional view, illustrating the means for adjusting the vertical height of the Chair back.

Similar reference characters designate corresponding parts throughout the several figures of the drawing.

According to the embodiment of the invention illustrated, the same includes in its organization:

Referring more especially to the features of the back structure B, it may be pointed out that the framework which supports the back rest comprises a transverse relatively wide web strap l (Figure 2) which carries suitable guide means 2 for cooperating with flanged portions of the bracket H so that the member l is vertically adjustable with reference to the bracket. 'A clamping screw, including a hand Wheel, and designated generally as 3. may be employed for looking the member l of the back structure in fixed position after being vertically adjusted on the swinging bracket H.

The transverse web strap I is provided at'its opposite ends with the upright frame members 4-4 connected by an intermediatecross-bar 5. The upper ends of the frame members 4 are provided with sockets or bearings da for receiving the laterally projecting pivot pins 6 mounted on the back rest R. The said back rest is preferably upholstered in an appropriate manner and extends above and below the pivots 6 as will be apparent from Figure 1 so as to present a. Substantially full length back rest for the occupant of the Chair.

The lower end of the back rest is provided with an angular abutment member 1, one leg 'la of which is secured to the bottom portion of the back rest frame. The cross bar 5' carries an adjusting unit in the form of a screw 8 which is intended to engage with the abutment 1.' The head of the member B is preferably provided with a rubber or felt cushion Ba* where it engages with the abutment 1 while the shank 9 of the screw is threaded into a tapped opening in the cross bar 5. Said shank 9 is provided with lock nuts lo and H on the portion thereof between the head and the face of the bar 5 into which the shank is threaded.

By manipulating the knurled portion of the screw head 8 it is apparent that it may be caused to move into and out of the bar 5 thereby to space the abutment l a greater or less distance therefrom for the purpose of adjusting the angular position of the back rest R on the pivots 6. This adjustment of the lower portion of the back rest permits the same to be moved inwardly or outwardly with reference to the seat thereby to readily adjust the back rest to that portion of the leg length of the occupant which rests on the seat A, and also Causes the upper portion of the back rest to assume a comfortable inclination for the shoulder portions of the occupant of the chair.' If the occupant of the Chair leans backwardly with greater force from his shoulders than between the shoulders and waist line, the back rest R will move outwardly near the top and inwardly toward the occupant at the bottom and the abutment 'I will pull away from the adjusting screw 8. In this case it will be apparent that the arms A acting as levers to tilt the back rest B' on the pivot B' will cause the rubber cushion element G' of the adjusting unit to readily compress because of the relatively great length of the leverage formed in the arms 4 between the pivots 6 and the pivot B'. On the other hand, if the occupant of the Chair leans forward but pushes rearwardly against the back rest at the waist line, it will be apparent that the load or pressure is imposed on the arms 4 of the back rest through the abutment 'I and adjusting screw 8. Thus, because of the relatively shorter leverage set up between the abutment 'I and the pivot B', it will be more diflicult or require more pressure to compress the rubber cushioning unit G' of the adjusting unit G. ,These factors all contribute to the efficiency of a posture' Chair which is intended to resist pressure from the occupant in various sitting positions thereby to aid in muscular exercise of the. Chair occupant.

Posture chairs of the type illustrated are preferably made of aluminum and are therefore comparatively light. As is well known, the Chair base E of swivel chairs is mounted on casters in accordance with the usual custom. Frequently; when it is desired to roll or propel the Chair on the casters, it is grasped by the upper portion of the back rest Which is the most convenient point of contact. If the back rest Were rigidly mounted in the arms .4, the force applied to the upper portion of .the back rest in attempting to move the Chair might result in tipping it over, because, frequently, the force applied in moving is greater than the weight of the chair which has a high center of gravity due to its light Weight.

I-Iowever, by mounting the back rest on the pivots 6 it will be quite apparent that if it is attempted to move the Chair by applying hand pressure to the upper portion of the back rest, the latter will swing before the Chair will tip on the casters, and, therefore, since the force has a shorter moment arm the Chair will not be tipped over.

Without further description it is thought that the features and advantages of the invention will be readily apparent to those skilled in the art and it will, of course, be understood that changes in the form, proportion and details of the construction may be resorted to within the Scope of the present invention.

I claim:

A back structure for chairs including a frame comprising spaced upright members, a web strap rigidly connecting the lower ends of said members, a cross bar connecting said members above the web strap, a back rest pivotally mounted near the upper portions of said uprights and extending substantially above and below the point of pivotal mounting, a downwardly extending abutment carried by the lower portion of the back rest, and an adjusting unit mounted on the cross bar and including a screw having a cushion head for engaging said abutment to change'the angu- Iar relation of the back rest to said frame members.

DWIGHT POWELL. 

